A charge of the CONFERS Technical Working Group (CTWG) is to discuss and refine the terms and language used by CONFERS in the discussion of rendezvous and proximity operations (RPO), on-orbit servicing (OOS) missions, and in-space assembly, servicing and manufacturing (ISAM).

Attachment A contains the list of terms under consideration in the CTWG.  The CTWG aims to provide consistency within CONFERS and other international organizations of RPO, OOS and ISAM terminology.  Terms in the lexicon generally have dictionary definitions, but in addition have more specialized usage in the context of on-orbit servicing and appear in this lexicon to clarify that specialized usage. As such, the CTWG presents the defined OOS/RPO/ISAM terminology for CONFERS below:

Lexicon Terms & Definitions – Released April 2022/Updated March 2023

An action which stops an on-board process and, if necessary, initiates an alternate process to put the servicer spacecraft and client space object in a safe and collision-free state.

The vehicle performing active GNC to accomplish RPO and pre-capture alignment with the Passive GNC Vehicle.

Traditionally on the Servicer Spacecraft, the active system involved in capturing the Client Space Object.

An agreed-upon three-dimensional space centered on the GNC passive vehicle (Client Space Object or Servicing Vehicle) where unintentional contact is possible within the passive anomaly recovery time and where ranging and active relative orbit control is needed for safety. Synonym for proximity operations control volume.  See Annex A Volumes and Zones

The act of effecting a rigid connection between a Servicing Spacecraft and a Client Space Object with the aid of a robotic arm.

The act of establishing a physical connection between two space objects.

An entity/organization procuring the service.

The space object being serviced by the Servicer spacecraft.

An operation executed by a space object relative to another space object to avoid contact for a specified amount of time.

A combined client space object and servicer spacecraft after Docking or Berthing.

An on-orbit service in which the servicer spacecraft maintains attitude stability for the combined stack.

On-orbit services enabling increased duration of client operations as a Combined Stack.

When a Servicer Spacecraft executes a controlled trajectory to affect a rigid connection with a Client Space Object.

A subset of proximity operations where the Servicer Spacecraft and Client Space Object intentionally perform mutually agreed actions to make and maintain physical contact.

Orbiting objects with no mechanical connection prior to initiation of capture operations.

First contact leading to a Berthing operation with the aid of a robotic arm.

Final rigid connection between vehicles; also period where vehicles are physically mated, and servicing activities may commence.

Sensing of a Client Space Object by a servicer spacecraft.

A minimum 3-D volume of space around the Client Space Object defined based on navigational uncertainty of each Rendezvous, Proximity Operations and Docking phase or any additional operational volume into which a Servicer Spacecraft may not enter without approval.

A type of capture employing magnetic forces to provide the initial non-rigid and/or the final rigid connection which enables servicing activities.

On-orbit activities to physically attach objects to each other.

Activities by a servicer spacecraft or servicing agent on a client space object which require rendezvous and/or proximity operations.

Configured with navigation fiducials and capture interfaces and/or servicing interfaces.

Traditionally on the Client Space Object, the passive system involved in mating the Client Space Object and Servicer Spacecraft.

The vehicle that the Active GNC Vehicle is navigating towards.

Note:  the Passive GNC Agent may either be Servicer Spacecraft or Client Space Object.

Orbital maneuvers performed between a servicer spacecraft and a client space object on a relative planned path within a pre-defined Approach Volume.

Synonym for Approach Volume.

Changing the orbit of the Client Space Object by a Servicing Vehicle.

Process wherein two space objects (at least one of which is a manufactured body) are intentionally brought close together through a series of orbital maneuvers at a planned time and place.

An entity/organization that provides in-Space servicing operations.

Spacecraft performing the servicing action.

Initial non-rigid connection between vehicles.

Action provided by Servicer Spacecraft to the Client Space Object, including but not limited to: inspection, capture, docking, berthing, relocation, refueling, life extension, removal, combined stack control, repair, upgrade, assembly, manufacturing, un-docking, un-berthing, release.

Terms Under Consideration

68 terms are under consideration by the CTWG for inclusion in the CONFERS Lexicon. They are:

  • Abort-Passive
  • Attitude Control Services
  • Augment
  • Automated
  • Autonomous
  • Co-Elliptical
  • Controlled
  • Cooperative Client
  • Co-Orbital
  • Credible Anomaly
  • Credible Failure
  • Departure
  • Drifting Natural Motion Circumnavigation
  • Dynamic Station Keeping (DSK)
  • Fail Operation
  • Fail Safe
  • Fiducial
  • Forced Motion Circumnavigation (FMC)
  • Free Drift
  • Foreign Object Debris (FOD)
  • Grapple
  • Grapple Feature
  • Grappling (verb)
  • Hold
  • Joint Mission Operations
  • Legacy Spacecraft
  • Mating Operations
  • Natural Motion Circumnavigation (NMC)
  • Navigation Data – Absolute
  • Navigation Data-Relative
  • Nominal Mission
  • Non-Contact Support
  • On-orbit Upgrade
  • Orbit Maintenance (Assistance)
  • Passively Safe
  • Passive Anomaly Recovery Time
  • Phases-Launch and Insertion
  • Phases-Rendezvous
  • Phases-Transfer
  • Radial/In-Track/Cross-Track Coordinate Frame
  • Refill
  • Refuel
  • Refueling Value
  • Relative Motion Coordinate Frame
  • Release
  • Removal
  • Rendezvous-Close Approach
  • Rendezvous-Far
  • Repair
  • Replace
  • Resident Space Object (RSO)
  • Resume
  • Retreat
  • Safe Orbit
  • Safety Zone
  • Secondary State Determination
  • Separation
  • Servicing Agent
  • Servicing Operation Termination (SOT)
  • Servicing Operations Initiation
  • Situational Awareness Data
  • Spacecraft Fiducial
  • Synchronized Time
  • Teleoperation
  • Towing
  • Un-Prepared
  • Upgrade
  • Waypoint